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Transversus abdominis plane (TAP) block using liposomal bupivacaine (LB) with bupivacaine hydrochloride (HCl) was more effective than bupivacaine HCl alone for reducing opioid consumption at up to 72 hours after cesarean delivery, according to a study in Anesthesia & Analgesia.
A total of 186 women with term pregnancies of 37- to 42-week gestational age were included in this multicenter, phase 4 study. All women were scheduled to undergo an elective cesarean delivery using spinal anesthesia. Participants were randomized to receive either a TAP block with 266 mg LB plus 50 mg bupivacaine HCl (n=97) or 50 mg bupivacaine HCl alone (n=89).
The primary endpoint of this study was the total opioid consumption after surgery through 72 hours. Additional secondary endpoints included total postsurgical opioid consumption through 24 hours, 48 hours, 1 week, and 2 weeks; time to first postsurgical opioid rescue medication; the proportion of opioid-free patients through 72 hours; and the proportion of opioid-spared patients at up to 72 hours.
Treatment with LB plus bupivacaine HCl was associated with reduced total opioid consumption through 72 hours compared with bupivacaine HCl alone (mean equivalent doses, 15.5 mg vs 32.0 mg, respectively; least mean squares difference, −16.5 mg; 95% CI, −30.8 to −2.2 mg; P =.012).
Area under the curve of imputed pain intensity score through 72 hours after delivery supported the noninferiority of LB plus bupivacaine HCl compared with bupivacaine HCl alone (147.9 vs 178.5; least squares mean treatment difference, −30.6; 95% CI, −75.9-14.7), with a corresponding prespecified noninferiority margin of 36 (P =.002).
No difference was found between the 2 groups in terms of postsurgical opioid consumption in an analysis of all treated patients, including patients who did not meet the inclusion criteria for the protocol-compliant analysis.
In a subgroup analysis, approximately 63.6% of patients had an adverse event (AE) following treatment with LB plus bupivacaine HCl compared with 56.2% of patients randomized to receive bupivacaine HCl alone. Only around 3% of patients in both groups experienced a serious AE.
Limitations of this study were the variability among participating sites in regard to their standards of care as well as the lack of participants who were at risk of postsurgical opioid use.
Despite these limitations, the investigators of the study suggest the use of a TAP block using LB with bupivacaine HCl “may be an important strategy in reducing overall postsurgical opioid consumption for the >1 million women undergoing cesarean delivery each year.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Reference
Nedeljkovic SS, Kett A, Vallejo MC, et al. Transversus abdominis plane block with liposomal bupivacaine for pain after cesarean delivery in a multicenter, randomized, double-blind, controlled trial. Published online July 21, 2020. Anesth Analg. doi:10.1213/ANE.0000000000005075
